Energy storage device



FIG. 1 is a first perspective view of an energy storage device showing the claimed new design;

FIG. 2 is a second perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The broken lines immediately adjacent to the claimed portions are boundaries, all other broken lines are environmental structures; all the broken lines form no part of the claimed design. 

CLAIM The ornamental design for an energy storage device, as shown and described. 